Field of the Invention
This invention relates to a voltage converter circuit and a voltage converter controller, especially to a voltage converter circuit and a voltage converter controller which includes an integrated circuit and capable of setting a parameter thereof without extra pins.
Description of Related Art
U.S. Pat. No. 7,315,190 discloses a voltage converter controller 200. This voltage converter controller 200 was implemented by an integrated circuit capable of reducing geometric size and cost. In order to set circuit parameters of the voltage converter controller 200, a discrete resistor Roc is connected to an output pin P4 of a power switch driver stage, and a default current source of the voltage converter controller 200 provides a current flowing through the resistor Roc to generate a voltage when the voltage converter controller 200 is in a start-up stage and does not enter a normal operating state yet. Then the voltage is sampled and held to set the circuit parameters of the voltage converter controller 200. Thus an extra pin is not required for the voltage converter controller 200 to setup the circuit parameters. Furthermore, the resistance of the resistor Roc can be adjusted to change the circuit parameters.
This prior art U.S. Pat. No. 7,315,190 can only set the circuit parameters during the start-up stage before the circuit enters normal operation, but can not set the circuit parameters during normal operation.